The present invention relates to the field of apparatus and methods for lifting small vessels out of the water and storing them when they are not in use. More particularly, the present invention relates to dock-mounted racks that are used to lift and store small boats.
When a small vessel, such as a canoe or kayak, is not in use, it is typically stored out of the water. In many instances, such storage requires that the vessel be lifted from the water and transported to a location away from the water or on a dock. Since these vessels usually weigh between 35 and 85 pounds and range in length from 9 to 17 feet, they are quite difficult to lift and cumbersome to transport, even over short distances, especially for one person.
Many small boat owners own or have access to a dock extending into the water. For these people, the most convenient place to store their vessels is on the dock. But when small vessels are stored on the dock surface, most of the dock width is obstructed, blocking access to the far end of the dock. Moreover, as there is typically a variance of 8 inches to 36 inches or more of freeboard between the dock surface and the water, lifting the boat onto the dock surface is clumsy at best if not impossible for one person and may result in damage to the boat and/or the dock and/or potential personal injury.
The prior art teaches a variety of hoists, davits and derricks for lifting small boats from the water onto the surface of a dock. The patent of Horton, U.S. Pat. No. 2,185,083, discloses a pivoting cradle by means of which a vessel is rotated into a sideways vertical position on the dock surface. Since the lifting force is provided by a winch mechanism on the dock side of the cradle, lifting from the water side is not enabled, and therefore one person cannot easily put the vessel into the cradle and then lift it without moving from the water side to the dock side. This necessitates a time-consuming two-stage process. The winch assembly and the lifted cradle also occupy considerable dock space and present an obstruction.
The patent of Anderson, U.S. Pat. No. 3,143,991, teaches a hoisting mechanism for lifting a dinghy onto the transom step of a larger vessel. It could also be adapted for use with a floating dock, but it would not be suitable for a fixed dock having a variable freeboard. Like the Horton patent, it achieves vertical storage on the surface of the dock, thereby creating an obstruction. Anderson also shares the disadvantage of Horton of requiring a two-stage attachment-lifting process, since it provides no mechanical advantage for lifting from the water side. Since the vessel is clamped at the gunwale to the lifting arm, moreover, this mechanism is useless for kayaks and can damage canoes and rowboats by the “pinching” stress placed on the gunwale. Additionally, this invention requires modification to the vessel itself as an “eye” must be attached the vessel to secure the hauling line. This invention also lacks a means of securing the vessel in a vertical storage position, unless the hauling line is secured to the larger vessel or dock, once it's lifted out of the water.
The winch-actuated derrick mechanism disclosed in the patent of Platt, U.S. Pat. No. 2,465,118, deploys a flexible cradle loop under the boat, thereby avoiding the “pinching” stress of the Anderson mechanism. But the flexible loop cannot secure the vessel in a vertical position for storage over the water on the side of the dock. The intent of this invention is to drain collected water from the boat and is well suited for its purpose; however, inasmuch as the derrick is rotatable and the flexible cradle is basically two sided, its function as an unmanned storage mechanism is inadequate considering the event of inclement weather. As with Horton and Anderson, the winch lifting mode requires a two-stage attachment-lifting process, and the derrick structure occupies a lot of space on the dock surface. The extent to which the mechanism can operate with a high freeboard is limited by the length of the horizontal boom and the span of the lifting cradle. This invention also lacks the operability from the waterside of the vessel.
In the patent of Lunsman, et al., U.S. Pat. No. 2,815,131, a cradle is formed by two horizontal bars that extend over the gunwales of the boat and two rope-like flexible elements that attach to the bars and extend under the vessel. Since the pivot points of the bars are fixed above the dock surface, the two rope-like flexible elements must be extended to accommodate freeboard variations from dock to dock or seasonally variations for the same dock; with increasing freeboard, however, this invention's purpose of lifting the vessel out of the water and turning the vessel on its side is diminished. This device also lacks a side support under the vessel once it's lifted, so that the sag of the flexible member will render the storage height above the water uncertain and unstable. Lunsman also shares the disadvantages of the other winch-actuated devices in terms of a two-stage operation and obstruction of dock space.
The apparatus taught by the patent of Lasko, U.S. Pat. No. 4,763,593, uses an L-shaped davit assembly under the vessel connected to a dock-mounted lever arm to tilt a boat into a vertical position. The downward extension of the davit into the water is adjustable, thereby accommodating freeboard variations. But, because the davit's pivot point is fixed at dock level, downward extension of the davit has two adverse consequences. Lowering the davit to adjust for dock freeboard increases the distance between the pivot and the vessel's center of gravity, thereby proportionately increasing the force the operator must apply to the lever arm in order to lift the boat. Since the length of the lever arm is fixed, lifting the boat will become quite difficult in high freeboard conditions. Lowering the davit also causes the storage position of the boat to extend further out over the water from the dock edge, which creates an obstruction for other vessels using the dock, as well as multiplying the stress on the davit assembly under windy conditions. Like the other prior art, Lasko does not enable single-stage cradling and lifting (i.e., in which the operator stays on one side of the vessel?) of the boat. The rotation of the lever arm downward to the dock requires the user to bend over pushing downward to the dock (which can cause back injury) where a latch mechanism engages and holds the cradle in horizontal position. Then the lever is lift back to the vertical and the rope is wound taught on the reel guide attached to the upper portion of the lever. To launch, the lever is released, and the operator's hands unwind the rope via the reel guide on upper portion of lever (which can also be ergonomically stressful—the greater the freeboard the greater the torque on the hands).
The patent of Palmer, U.S. Pat. No. 2,294,864, teaches a U-shaped davit, which is pivotally mounted to the stern of a large boat or the side of a floating dock. As with the Anderson patent, this apparatus is useless on a fixed dock that's subject to seasonal freeboard variations. Even as applied to a floating dock, this device becomes very inefficient for freeboard heights of less than a foot, because the reduced length of the lever arm will demand excessive torque to turn the winch. Although the Palmer mechanism provides a more stable storage position with less dock obstruction than the other prior art, it uses hooks to attach the davit to the gunwales of the boat, thereby subjecting the sides of the vessel to potentially damaging pinching and shearing stresses. Since, like the other prior art, the Palmer device does not enable water-side boat lifting, it requires a burdensome two-stage operation.
The foregoing review of the prior art reveals the following principal deficiencies:
1. Obstruction of dock space by the lifting apparatus;
2. Obstruction of dock space by storage of the boat over the dock surface;
3. Two-stage operation: first water-side boat attachment, then dock-side lifting;
4. No means available to operate from the waterside only;
5. No means available to operate from the waterside or dockside at the user's option;
6. Inability to accommodate variable dock freeboard;
7. Excessive lifting force/torque;
8. Lack of stability in the vertical storage position;
9. Potentially damaging shear stress on boat and/or dock sides during lifting;
10. Modification to the vessel itself; and
11. Complicated installation and de-installation for winter storage.
The present invention overcomes these deficiencies by providing a three-sided cradle that is rotatably connected to two lateral supports extending outward from one side of the dock. A person in the water can float the canoe or kayak into the cradle and lift it into a secure vertical storage position on the side of the dock without having to get up on the dock. A pivot point extending out into the water having the ability to be positioned above or below the dock surface has the advantages of both accommodating freeboard and minimizing and maintaining a constant distance between the pivot and the boat's center of gravity, thereby allowing for much less effort in lifting. Depending on the depth of the vessel, the cradle can be dimensioned so that the position of the vessel's center of gravity tends to hold the cradle in a vertical or past-vertical alignment after it's been lifted. Where needed, a cradle latch that can be activated from the water side further secures the storage position. With attachment of a tether cord, the lifting operation could also be performed from the dockside of the vessel and at the user's option.
For purposes of spatial orientation, in the specification and claims for the present invention, the following definitions will be used:
“Longitudinal” or “longitudinally” means the direction in which the dock extends outward into the water, i.e., in the direction of the dock's length;
“Lateral” or “laterally” means the direction perpendicular to longitudinal, i.e., in direction of the dock's width;
“Horizontal” or “horizontally” means in a plane parallel to the surface of the dock;
“Vertical” or “vertically” means in a plane perpendicular to the surface of the dock;
“Loading position” means the orientation of the present invention with the centerline of the cradle in the horizontal plane;
“Storage position” means the orientation of the present invention with the centerline of the cradle in the vertical plane;
“Proximal” means that part of a component of the present invention which is nearest to dock when the present invention is in the loading position;
“Distal” means that part of a component of the present invention which is farthest from the dock when the present invention is in the loading position;
“Upper” means that part of a component of the present invention which is farthest from the water surface when the present invention is in the loading position;
“Lower” means that part of a component of the present invention which is nearest to the water surface when the present invention is in the loading position;
“Inward” or “inwardly” means in the direction toward the centerline of the cradle; and
“Outward” or “outwardly” means in the direction away from the centerline of the cradle.
Unless otherwise specified, the described orientation and/or position of a component of the present invention is given with reference to the loading position.